Two-way wireless communication systems that support calls to the public switched telephone network (PSTN) are well known in the art. Examples of such systems include cellular telephone systems and trunked radio systems. Additional known systems include city-wide telepoint systems based on second generation cordless telephone (CT2) technology. This latter technology provides service within small, isolated "islands" of coverage, each defined by a limited radio coverage range provided by one or more fixed communication units, i.e., base stations, located therein. Unlike cellular telephone systems and trunked radio systems, CT2 citywide telepoint systems typically have hundreds or even thousands of base stations, each individually interconnected with the PSTN. As each call within a specific coverage range is received from portable communication units (PCUs), a base station providing coverage within the range typically authorizes the call and couples the call to the PSTN. Information about each call, such as call destination and length of the call, is thereafter periodically forwarded across the PSTN to a network control center, which usually controls the base stations providing service within a geographic area. The network control center, in response to receiving the call information from each of the base stations providing coverage within the geographic area, updates billing information corresponding to system subscribers.
The information collection process is typically performed once a day, usually at a time such as during early morning hours when the PSTN has little traffic. A telepoint service provider may thereafter provide itemized bills, perhaps monthly, to the subscribers registered on the system. In some circumstances, however, the current billing process may pose a problem if updated billing information is needed more often than the call information is collected, e.g., once a day. Such a circumstance could arise, for example, if the telepoint service provider desires to provide rental PCUs to subscribers needing only temporary portable telephone service. In this case, the telepoint system must be capable of authorizing each call made from a rental PCU to prevent the temporary subscribers from receiving service for which they have not paid. Furthermore, the telepoint service provider must be able to provide itemized billing statements to the temporary subscribers upon return of the rental PCU.
One solution to this problem would be to implement a system in which every call from every PCU within the system would be authorized by the network control center at the time of the call. This solution would further require that the base station immediately transmit the call information to the network control center at the termination of each call. In response to reception of the call information, the network control center would update the billing information for the subscriber, whether temporary or full-time. Such a solution is not feasible for use with the current telepoint system, however, because the network control center may be coupled to thousands of base stations by the PSTN, the capacity of which would, in all probability, be exceeded during peak business hours. Although the addition of dedicated telephone lines between the network control center and each base station might provide for such an excessive amount of communication, the thousands of necessary telephone lines could only be installed at great expense, the end result of which would be a substantial increase in the cost of telepoint service.
Thus, what is needed is a method for selectively authorizing calls in real time in a telepoint system. This method should, in addition to providing for the authorization of selected calls in real time, provide for the updating of billing information as each call is terminated. Furthermore, the employment of the method should prevent the overloading of the capacity of the existing PSTN during peak business hours.